//思路：双指针

import java.sql.Array;
import java.util.*;

public class Solution {
    public static void main(String[] args) {

    }

    public void reverseString(char[] s) {
          int i=0,j=s.length-1;
          while(i<j){
              char t=s[i];
              s[i]=s[j];
              s[j]=t;
              j--;
              i++;
          }

    }
    

}













